1. Field of the Invention
The present invention relates to a creep-proof and corrosion-resistant nickel-based alloy for use in high-temperature technology.
2. Discussion of Background Information
Increasingly, higher mechanical and corrosion chemical demands are placed on metal materials at operational temperatures of more than 900xc2x0 C., in particular for hot work tools, for components of gas turbines and motors, for elements in oven construction, and in chemical industries. Due to corrosion wear and also in view of the toughness and the creep characteristics of the material, nickel-based alloys containing chromium are well-suited for use at very high temperatures.
A nickel-based alloy with the abbreviation NiCr 7030 according to the DIN material number 2.4658 is considered heat-resistant and is used for heat conductors, oven components, and the like. Although such a material has good oxidation resistance, depending on its silicon and aluminum content, it is also provided with a low toughness and low time yield as well as high creep values at operational temperatures of approximately 1000xc2x0 C.
A nickel-based alloy that is resistant to high temperatures is known from DE-C-4411228. This high-temperature-resistant, oxidation-resistant, massively nitropenated, hot and cold formable nickel-based alloy is essentially composed of (in mass-%) 0.001 to 0.15 carbon, 0.10 to 3.0 silicon, 25.0 to 30.0 chromium, more than 0.3 to 1.2 nitrogen, 0.001 to 0.01 boron, 0.01 to 0.5 yttrium, cerium, lanthanum, hafnium, and tantalum, alone or in combination, the remainder being nickel with a content of at least 64.0%. Although a mixed crystal hardening can be achieved due to the carbon content, the primarily effective elements of the above-mentioned alloy with regard to the high-temperature characteristics are chromium and nitrogen. Chromium and nitrogen form chromium nitrides which improves creep characteristics, with nitrogen additionally providing a mixed crystal hardening. Considerably improved creep characteristics and heat resistance values seem achievable using the alloy according to DE-C-4411228.
In the temperature range between 900xc2x0 C. and 1200xc2x0 C., a so-called creeping of the material during stress and a worsening of corrosion resistance occurs, in particular during cyclic wear, in conventional nickel-based materials, which are exposed to higher wear to an increasing extent. The object of the present invention is to remove these shortcoming and to create an improved nickel-based alloy for high-temperature use.
The object according to the present invention is attained in a creep-proof and corrosion-resistant nickel-based alloy comprising in wt-%:
0.0015 to 0.60 carbon (C)
0.20 to 0.90 nitrogen (N)
22.0 to 32.0 chromium (Cr)
5.0 to 20.0 elements of group 4, 5, and 6 of the periodic table, except Cr
0.03 to 3.0 aluminum (Al)
0.4 to 3.0 silicon (Si)
up to 0.15 elements of group 3 of the periodic table, except actinoids
up to 0.60 manganese (Mn)
up to 14.8 iron (Fe)
up to 0.01 boron (B)
a maximum of 0.014 phosphorus (P)
a maximum of 0.004 sulfur (S)
a minimum of 51 nickel (Ni) or a combination of nickel (Ni) and cobalt (Co) and melting-related impurities.
Thus, the present invention is directed to a creep-proof and corrosion-resistant nickel-based alloy for the use in high-temperature technology comprising, in wt-%:
0.0015 to 0.60 carbon (C);
0.20 to 0.90 nitrogen (N);
22.0 to 32.0 chromium (Cr);
5.0 to 20.0 elements of the groups 4, 5, and 6 of the periodic table, except Cr;
0.03 to 3.0 aluminum (Al);
0.4 to 3.0 silicon (Si);
maximum of 0.014 phosphorus (P);
maximum of 0.004 sulfur (S);
minimum of 51 of nickel (Ni) or a combination of nickel (Ni) and cobalt (Co); and
melting-related contaminants.
The carbon can be present in 0.16 to 0.5 wt-%.
The ratio of nitrogen to carbon can be 0.5 to 5.5, preferably 1 to 4, and optionally 1 to 3.
The nickel-based alloy can contain a total concentration of molybdenum (Mo) and tungsten (W), in wt-%, according to the following formula:
Mo+W/2=3.0 to 10.0, preferably 4.0 to 8.0.
The Cr can be present in 25.0 to 30.0 wt-%.
The Si can be present in 0.5 to 1.0 wt-%.
The nickel based-alloy can comprise at least one element of Group 3 of the periodic table, except actinoids, the at least one element being present up to 0.15 wt-%, preferably 0.01 to 0.12; manganese (Mn), the Mn being present up to 0.60 wt-%; iron (Fe), the Fe being present up to 14.8 wt-%; and/or comprising boron (B), the B being present up to 0.01 wt-%.